Different polymer materials exhibit varied and different physical characteristics. It is often the case that a polymer has excellent physical properties in one area but has poor physical properties in other areas. As an example of this consider silicone rubber. While silicone rubber has excellent heat resistance, it also has poor oil and abrasion resistance in comparison to some organic polymers.
It would seem then that a simple solution would be to mechanically blend different polymers together, each having complementary physical property profiles, so that the resultant polymer blend would exhibit the superior physical properties of each component in the blend. However, the reality of the situation is that such polymer blends usually exhibit inferior physical properties.
One reason for this is the fact that polymers may have different curing mechanisms. That is, whether the polymer crosslinks by hydrosilation, condensation, etc., will determine the rate at which the polymer will react to final cure. If two or more dissimilar polymers are present and each of them cures independently of the others the result will be regions where the polymer blend is rich in one polymer and deficient in the other polymer(s).
On the other hand, if the cure mechanism is the same for two or more polymers the polymers will intercrosslink at the same rate with each other during final cure. The result is an interpenetrating polymer network that is homogeneous in each reactant.
Therefore, it is theorized that if polymers with different curing mechanisms can be compatiblilized by modification of the curing reaction in one of the polymers it will be possible to covalently bond two or more dissimilar polymer materials to take advantage of the superior physical properties of each polymer. Such a compatibilizer, then, will adapt one polymer material to chemically combine with another.
In addition, compatibility is also determined by the nature of the polymers themselves. That is, when organic and silicone polymers are blended together phase separation may occur between the organic and silicone materials. Therefore, it is also theorized that dissimilar polymer components in a composition should be compatibilized by covalently bonding to one of them a material which avoids this phase separation.
U.S. Pat. No. 4,650,849 (Nishimuar et al.) discloses a photosensitive curable resin composition comprising an organosilicon compound having amino and vinyl functional groups; a tetracarboxylic acid anhydride, and a diamino compound.
U.S. Pat. No. 4,659,851 (Plueddemann) discloses organosilicon compounds that will cohesively bond polyorganosiloxane elastomers and resins to inorganic and organic substrates. The organosilicon compounds comprise alkoxy, hydroxy, and vinyl functional siloxanes and silanes.
U.S. Pat. No. 4,365,042 (Cooper et al.) discloses compatibilized compositions containing polyphenylene oxide and EPDM-silicone rubber using fumed silica filler as the compatibilizer.
U.S. Pat. No. 4,201,698 (Itoh et al.) discloses the use of an organopolysiloxane having aliphatically unsaturated functional groups and mercapto functional groups to react with a natural rubber or a synthetic rubber.
U.S. Pat. No. 4,150,010 (Itoh et al.) discloses the use of an organopolysiloxane having mercapto functional groups to react with an ethylene-propylene copolymeric elastomer.
The compatibilization of EPDM rubber with an elastomeric organopolysiloxane by the use of silica filler is described by Mitchell and Wada, A New Performance Elastomer Composition, American Chemical Society, 127th Meeting of the Rubber Division, Los Angeles, CA, April 23-26, 1985.
It is an object of this invention to produce a polymer alloy composition comprising two or more polymers having different curing mechanisms and further comprising a compatibilizer to adapt the curing mechanism of one or more of the polymers so that the composition will cure the same way.
It is further an object of this invention to provide a process for producing polymer alloys.
Other objects will become apparent upon reading this specification.